I've just spent the day replacing the clutch and rear main seal on the 16v RS.  During disassembly I've found a cracked pipe to be welded(for later).

Reassembly and clutch adjustment went well, but I've done something wrong with the wiring.  I've now run out of energy and motivation to chase it any further tonight.  All lights working as expected, starter turns fine, sidestand stops the starter from turning as it should.  So what's wrong?  The cooling fan runs as soon as I turn the ignition on and the engine won't fire.

It's a 92 RS-16v (non ABS model), so early Motronic.  The only wiring that got disturbed was battery, computer, alternator, starter motor, rear lights.

Al

If the temperature sensor has a dead short to earth it will make the fan run and prevent it from starting because the "brain" thinks the engine temperature is over 113°C.
How that would happen doing a clutch is another question.

a clear head and a nights sleep might help al

rick is on the money there ...check it tomorrow

washer clamping a cable some where ?

Good to know that Rick.

When I get back to it(going away tomorrow for Easter), I'll probably just disassemble all the electrics above the gearbox, then reassemble slowly and double check each and every connection. It's not a big job.

The cracked exhaust was a surprise (I do know they have a habit of cracking),the bike showed no popping, backfiring or any extra noise. I have a spare pipe that's in good shape will use that most likely.

Al

Well, I finally got to it today.

The original exhaust had a cracked #1 header, thankfully I had a spare system from the written off 11LT so thats now fitted.

For the wiring I pulled it all out had a look, found nothing wrong, put it all back together and now it starts.  Must be my magic fingers I guess.  And the fan isnt running anymore either.

Al

woohoo  ....win !

RicK G wrote:If the temperature sensor has a dead short to earth it will make the fan run and prevent it from starting because the "brain" thinks the engine temperature is over 113°C.
How that would happen doing a clutch is another question.

That would be correct on a Jetronic equipped bike,
where the sensor(s) is connected to ground.

On a bike with Motronic the temp sensor(s) have no ground connection,
it's connected in a loop.
The Motronic sends out a 5V signal, and reads the voltage drop through the sensor.

Is it feasible that the problem could have been caused by the connecting plug into the computer not making a secure electrical connection on each pin and the simple at of opening and reconnecting them might have solved it? With the age of the Ks generally I am always a little more inclined to first suspect the electrical connections between the components rather than the components themselves.

There's a good chance of that (the poor connection at the computer).  No signs though, all the connectors and pins are in excellent condition, no corrosion/powder of any sort in the computer plug.  externally, though not important the motronic casing is covered in corrosion pitmarks etc, as is the battery carrier and more.  All from being stored outside in the weather for 5 years under a plastic tarp.

Al

I have already discovered on the K that the tabs and pins can be in excellent condition but if any one is even slightly bent it still looks in perfect condition but is not making electrical contact with the usual consequences. The connectors to the computer and also the under tank connection for the fuel pump have already done this on my K. When I changed the computer I took a small sliver of P2500 wet and dry and used in the dry to clean up the tabs and pins. I did same with fuel pump connections. I then had a further problem solved by crimping up all the connecting tabs ever so slightly. All I can say is looks can be deceiving.

If your loop was broken by this happening then it might explain the problem in a way that underlines the fact that all your work was 100% correct in the first place.